Reverberation apparatus



13, 1940- 1.. HAMMOND 2,211,205

REVERBERATI ON APPARATUS Filed oct. 7, 1939 2 Sheets-Sheet 1 k 0 I I/kz/en zor W i i 2 lau/ ens' flammo/za Aug. 13, 1940; L. HAMMOND v 25 30REVERBERATION PfARAws Filed Oct. 7, 193 9 2 Sheets-Sheet 2 [/2 1/ 9/2 1or Laurensffammond Patented Aug. 13,1940

f REVERBERATION APPARATUS,

I Laurens Hammond, 'chicago lll. Application October 7,1939, Serial Nq.298,366

My invention relates'generally to reverberation apparatus such 'as thatdisclosed in my co-pend ing application, Serial No. 284,761, filed July15,

1939, and more particularlyto a'protective locking apparatus'forholding'the parts therein in position when the apparatus is being shipped ormoved about.v

In the apparatus more fully disclosed in the aforesaid applicatiomthe'reare a number of rel- Y ativelylong coil springs-utilized to transmitsound vibrations from an electr'o-mecha'nical transducer to amechanico-electric transducer, the system providing several points atwhich the vibrations traveling through the springs are reflected and 5other points at which the vibrationsare damped,

so'that the over-all result ofthe transmission of the sound through,thiscoilispring system is the introduction of a reverberation effect ofthe signal ytransmitted In this apparatus the relatively long coilsprings are preferably under slight tension and are supported by levers.These supporting levers, are

preferably made as light in weight as is compatible with their necessarystrength to support the springs. The factor of safety employed in V thedesign of these supports for the springs is r I therefore made very'lowsince, if'thesupportswere of large mass, they would introducean'un--desirable effect in the transmissionfof the signal vibrationsthrough'the spring,j sys'tem=f.- 'Thus'; it.

the springsupports are subjected to any forces f greater than thoseencountered in the-"normal use of the apparatus, such forces mightreadily strain the supports beyond their elastic limits and thus .35deform or break them. The springs have considerable mass ,and theytherefo'retransmit excessive forces to their supports if they are sub-j.

jected to asudden shock, due to their relatively great momentum orinertia.

. provide means for optionally locking theends of the sound wavetransmitting coil springs of a reverberation apparatus so as to preventtrans-- mission of destructiyely large forces to the spring supports- IA further object is to provide an improved locking means for thesoundtransmittingsprings of areverberation apparatus, whichis simple inconstruction, is easily operated, which will not dam- .age the springs,which will not interfere with the I operationmf the apparatus when inunlocked position, and'which can be economically inanufactured. 7 4Other objects will appear from the following It is thus angobject of thepresentinventionto description; reference being-had to theaccompanyingdrawings'in which:

Fig. 1 is a side elevational view of the apparatus, a portion thereofbeing broken away to show the operating parts more clearly;

Figs. 2, 3 and 4are enlarged transverse sectional views taken on thelines2-2, 3-3 and 4-4 respectively of Fig. 1; i

Figs. 5, 6 and 7 are vertical sectional views taken on the lines 5-5, 5--6, and 11 respectively of Figs. 2, 3 and 4; V

Fig. ,8 is an enlarged fragmentary sectional view illustrating themanner of the engagement of the locking plate with one of the coilsprings.

As shown in Figs; 1 to 4 inclusive, the reverberation apparatuscomprises a frame. composed of four upright angles I0, ll, l2 and I 3,which are I secured togetherby means of flanged plates or shelves l4to-2li inclusive, these shelves being riveted or bolted. to the verticalangles ID to l3.

The apparatus is adapted to be supported by rubber cushion supports 22,23 and 24 so as to be substantially insulated against minor vibrationsfrom the apparatus to which it may be attached.

As more fully disclosed in the aforesaid application, anelectro-mechanical transducer 26 is secured to the shelf l5. Thistransducer maybe similar in construction to the motor portion of a."loud speaker. V Instead-of actuatinga diaphragmas in theloud speaker,the vibrations generated bythe moving voice coil of thespea'ker'aretransmitted to a stirrup 28 througha wire .30, the wire 30being secured to the voice coil carrying spider and having its upper endsecured to the end of a freely pivoted lever 32." I i A spring A issecured' to the other end of the leveriiZ by means of a wire34,the'spring A depending into a'tube 36 which is suitably supportedfrom the shelf 20 and extends through apertures in the plates I1,"IB and19. The lower end of the spring A is anchored adjacentthe bottom of thetube 36, and the latter is substantially completely filled with a liquidsuch as light oil, so that Viv brations transmitted to the. spring A aredamped.

;The stirrup 28 serves as a-support for a pair of damping springs Bland' B2, which project downwardly into tubes 38 which are likewisesubstan- "'tially filled with oil and are supported in a man ner similarto'that in which the tube 36 is supported. These/springs BI and B2 arelikewise anchored at the lower ends of the tubes 38, and thus serve asdampers to improve the frequency response char cteristics of theapparatus as a whole. i Y

Alever 40 is pivotally secured to'the stirrup 28 I D is secured by astrap 44 with a hook 45 forming -C is anchored within a tube 42 whichcontains a damping liquid immersing the lower end portion of the springC. The lower endof the sprin part ,of a mechanicoelectric transducer 48.This transducer may be any suitable crystal, ca-;

paci y, Or other high mechanical impedance pickup, and issupported by arod 50, the latter being secured. tothe shelf I9 in a manner permittingward movement on the'actuating barhy a ,pin 10, and an arm. 121 which.has a slot. for; v g I alienating sleeve 108N at i ins peened tovertical adjustment ofits position. 4

The springsA,' Bl,'B2-, C and Dare relatively long and are preferablyunder slight. tension. The supports for the springs such asthexlevers 32and 40 and the stirrup 28 -are therefore stressed close tov theelasticlimit of the material of which they are madeiallowin'g a smallfactor of] safety) because these parts should be of as small mass aspossible inorder to obtain the proper sound vibration transmittinglcha'r- Because of thefact; that the supports ,for the springs are thusmade relatively fragile; they would be 5115-;

acteristics' of the system as a whole.

ceptible to deformation and breakage during shipment or rapid movementof the apparatus,

were: not the locking means of the present-in I vention provided toprevent the transmission of supports.

The means for locking the ,springs'to prevent ,the spring supports frombeing. subjected to.

v thus, clamp the/latter against movement..." The "plates 52 and 54. ThelockingplateiZ is mounted excessive strains comprises a pairof lookingfor sliding movement above the shelf l6, being guided for substantially:r'ectilinear r'n'ovement."by a shouldered bolt 56 which is securedftothe shelf l6 and projects, through a slot 58 formed in.

plate 52. The other end of the locking plate .52

is held in'engagement with the top surface of receiving the bar 66.. 1

The end of, the arm '|2 is pivotally connected with the plate 52 by 'ashouldered-rivet H,"the lower endof which projects through a .suitablehole-in the plate 62. The shelf [6 may have a groove formed" therein forthe endof the rivet 1 '14 as shown by the deformation 15. in'Fig'ure 5.

The locking plate -52 hasa pluralityof circular openings 11 'to 8|inclusive through which the springs A, C, Bl, vB2 and -Dpass freely, andwhich register with. corresponding openings formed in the plate I6;:The-edgesof' the openings TI to 8| inclusive are beyeled'as' best shownin Fig. .5, so that when the locking plate 52' is moved in.the'direction' of the'arrow (Fig. 2) ,the' beveled edges surroundingthese openings will en-' gage the springlin the Fig. 8. v

From Fig. 8 it will, be noted that as..the'1ock-' 'ing. plate 52 isshifted. in the "direction er the" arrow, the beveled edge surroundingits opening gage the wall of the registering opening. in the shelf 16,whereupon thebevel edge will wedge manner illustratedinbetweensuccessive coils of the spring BI, and

thus clampthe spring sum'ciently tightly to prevent 'the transmission ofany appreciable force through the portion of the spring thus locked. Theillustration of Fig, '8 is representative of the manner in which all ofthe .springsare held v.by the locking plate when it is moved to lookingposition. v v V The'locking plate 54 shouldered bolt 82 which is similarin construction to the bolt 56 and is provided with a spring pressedwasher 84, thebolt extendingthrough an elongated slot 86 in'the plateil. The plate 54 is movedbyme'ans of an arm 8.8 whichis slotted toreceive the actuatingbar 66. and ispressed downwardly to'hold the pIate54 in en? 4 is 'guided fbr sliding movement with respect to the shelfl9v by a of a rivet 95, similar to. ,the rivetl "shown, in I I Fig- :Plate 54 serves as a means to clamp the lower end of the spring D. only,since the lower ends of the other springs are anch'ored 'in'the ltubes'into which they extend, The locking plate 84 istherefore suitablyconformed with an enlarged opening; which-embraces the tubes 38. and 42,one edge 81 0f said opening fl bei ng beveled so as tobe capable ofengaging be- P tween'successive turns of thecoil spri n'g D and plate 54isalsojprovlded "with an enlarged cir- 'Qposition by a spring washerwhich is com pressed between the depressed portion of the shelf l9 and-acollar [02 which is pressed over the sleeve 96. I The lower end of theactuating bar 66 ex- ?tendsjthrough a suitable (slot f formed in a bear-I in'gf disc 1 04; .vvhich" is rota'table in .an annular I internalgroove;l0 6.-.formed at the lower end of --.'the'.actuating.bar 86 andis Qheld thereon by a cotter ;pin-, H2. Itwill'be understoc'id thatthesp'rings 64 and 9.0 ,t'end to'raise the:actuatin its groove 10B.

ing bar 66, and-thus hold thebearing "disc IM' 'A'rod lll is pivo'tallyseedredtdtneend r the arm. I M and;has a handle knob H8 secured at itsouter end. ,1 'Ijhe rod I'll' has ailatportion: H8 and two notches;linens I22 at the end 'oi' the rod, "H4 is pressed downwardly adjacent,1 the bracket I24 by; a leaf spring; I26, so; that when the rod is ineitherof its extreme positions itwill lie-pressed downwardly to causeinterlocking engagement of its notch l2ll or notch l22iwith l thebracket I.

Whenv the parts are in v the positions-in which they are illustrated inthe drawings (except Fig.

8), the'springsare free to transmit sound .vibra tions from end to end,and the apparatus 'will operate in a normal manner to transmit andmodify vibrations from the electro-mechanioal transducer 26 to thepick-up 48. When it is desired to move the apparatus or prepare it forshipment, the knob H6 is raised slightly to disengage its notch I20 fromthe bracket I24 and pushed inwardly (in the direction of the arrow,

- Figs. 4 and '7) until the knob H6 abuts the bracket I24. When'theknobis released in this position, its notch I22 will be forced into and heldin engagement with the bracket I24 by the spring- I26. Such movementofthe knob H6 will cause the; actuating bar 66 to ,rotatecounter-clockwise (Figs; 2 and 3) with consequent movement of thelocking plate 52 to the-right (Fig.2) and 3). Asthe locking plate 52moves; to the right, the beveled edges surrounding the openings TI to 8!thereof willengagetheir respective springs'A.

(3, Bl, B2 and'D inltlie manner illustrated in ,transmission of forcesfrom a. portion of the spring on one side of the locking plate to theportion on the opposite side thereof} Similarly, the locking plate 54will engage and hold the lower end of 7 spring D.

When it is desired I -pulled outwardly"whereupon .all "the parts will 30move in directions opposite to. those indicated' by the arrows, and thelocking plates will be disengaged fromthesprings. In the event thatthespring inove with the locking plates'due to the fact that the lockingplates are frictlonally wedged between successive 'coils'of thesprings.-

the springs will be freed from the locking plate as the locking platesapproach their normal positions due tothe abutment of the springs withthe edges 'bf the openings in the adjacent shelves.

The springs arelentirelyclear from contact with fiparts of thelocking-means when the latter are in unlocked position. so thatthere isno possibility Fig. 8, thusholding the springs toprevent the again toconditionthe apparatus'for operation; the knob -I I6, is --raised andvibration transmitting coil spring, a rigid frame j and relativelyfragile means for supporting said spring. in said rigid frame, thecombination of an element rigid with respect to said frame and having aportion adjacent the end of said spring near said fragilesupportingmeans, and a-manually operable locking element movable towardsaid rigid element and having a sharp edge engageable between successiveturns of said spring.

2. In a reverberation apparatus, the combination of a frame having apluralityof apertured transverse plates, a sound vibration transmittingmovement of the-.locking plate 54 to the left (Fig:

of interference withthe transmission of sound;-

vibrations through the springs by any parts of the locking means.

Furthermore. because of the beveled edges provided on. the lockingplatesfor engagement with f the springs; therezis no dangerfof damaging thesprings by operation-of the lockingl'mean's .even' if. the parts" arenot manufactured to very closei tolerancesx I'lie'lockingplateSJbecauseof their i "engagement between successive turns ,01 the springs;completely prevent the transmissionof forces longitudinally. of thesprings past the plates at which they are locked. Because of the 5provision of this locking means. it is possible to assemble thereverberation apparatus completely and ship it to'the placewhere it isto be, used.

"whereas if this locking means were not provided it .would be necessaryto ship the apparatus in par- ;tially assembled condition, and .tocompletethe,

assembly at the placeof use. r

While I- have shown and described a-particular embodiment of myinvention itwill be apparent to those skilled-in the art that numerousmodlficaa 35 .tions and variations may be made in the form andconstruction thereof. without departing from the more fundamentalprinciples of the invention. I therefore desire, by the followingclaims. to

. include'within the scope of my invention all such '0 similar andmodified forms of the apparatus disclosed, by which substantially theresults of the invention may be obtained by substantially the same orequivalent means. J

Iclaim: I r '5 '1. In a reverberation apparatus having a sound saidspring,

. spring extending through an aperture in one.of

said plates, relatively fragile means supporting and manuallyoperable/locking means,

mounted on one of said-plates and engageable with saidspring near/its.supporting means to prevent transmission of forces of'destructive magniv,tude to said supportingmeans- 3. In a reverberation apparatus, thecombinationof arelatively long coil spring, a rigid frame.-

ywork, relatively-fragile means connecting said spring to said frameworkfor-supporting the former; and manually operated means carried bysaidrigid framework for locking a portion of said spring adjacentsaidfragile meansto said framework, thereby to prevent transmission ofappreciable-1forcesfrom -said Spring to said fragile means.

. 4., In a reverberation devicecomprising a rigid frame having a,plurality of 'apertured horizontal shelvesand a sound transmitting coilspring extending through the apertures insaid shelves, jfthecombinationof a locking plate movably mounted on one of said shelves, said platehaving an opening normally in substantial registration with an aperturein the adjacent shelf through which said spring e xtendsfand means .tomove said locking plate relative to said'shelf, thereby locking saidcoil spring between'the edge of the aperture in" said' shelf and th ingin said locking plate,

5.3m a reverberation apparatus, the combination of a framehaving' aplurality of apertured transverse plates, a sound vibration transmittingspring extending through apertures'in said plates, relatively fragilemeans securedto the ends -of 'saidj spring. respectively, and manuallyoperable locking elements engageable respectively with said spring nearits ends to'prevent trans-.- mission of forces of destructive magnitudefrom said spring-to said fragile means;

edge of the open 6. In areverberation apparatus, the combination' of arelatively long coil spring, a rigid framework, relatively fragile meansconnecting said spring. to said framework for supporting the "former,and a manually operated mechanism for locking the end of' said springadjacent said fragile means to said framework thereby to preventtransmission of appreciable. forces from said spring to saidfragilemeans, said manually operated locking mechanism having latchingmeans associated therewith selectively to latch it in locked orunlockedposition'. f x

7. In a reverberation device comprisinga rigid frame having a7 pluralityof ap ertured hori-' zontal shelves and a sound transmitting coilspringextendlngthrough the apertures in said shelves, the combination ofa pair of a locking plates, said plates having openings normally insubstantial registration I with theapertures in said shelves throughwhich the ends of said spring extend, and means to move said lockingplates 1 relative to said shelves, thereby locking the ends of said coilspring between the edges of the apertures in said shelf and the edges ofthe open-- ings insaid locking plates.

8. In'areverberation apparatus, the "combination of an elongated frame,a sound vibration transmitting coil spring extending longitudinally ofsaidfra ne. relatively fragile means carried by said frame andsupporting-saidspring, and

manually operable locking' mean's' engageable with 'said spring near itssupporting means to prevent transmission of forces of destructivemagnitude to said supporting means,'sa id'1oc'king' -means including awedge-shaped partqforengagement between successive turns .ofsaid-coilspring fragile r'nean's to said -framework thereby to preventtransmission'of appreciable forces from said spring' to'said-fragi1emeans, saidlocking' means including a locking part engageable betweensuc-. cessiv, turn's'of'said. spring; and means to hold said lockingmeans selectively in locking or unlocking position; v I 1 I Y LAURENSHAMMOND.

